diff --git a/swash/processing/post.py b/swash/processing/post.py
index 0376bf8..daf9010 100644
--- a/swash/processing/post.py
+++ b/swash/processing/post.py
@@ -84,7 +84,7 @@ ax_r.grid()
 fig_x, ax_x = plt.subplots()
 ax_x.plot(-botl[0, :], color='k')
 ax_x.plot((dep-botl)[t == t0, :].T)
-ax_x.axvline(x0)
+ax_x.axvline(x0, c='k', alpha=.2)
 ax_x.set(xlabel="x (m)", ylabel="z (m)")
 ax_x.autoscale(axis="x", tight=True)
 ax_x.grid()